# 🏅 Week1 - typescript 練習
**本週學習重點:**
1. 基本型別 number, string, boolean, undefined, null,
2. 任意值 any
3. 型別推論 type infer
4. 聯合型別
5. interface 介面/接口 ( 可選屬性/任意屬性/唯讀屬性 )
6. array 數組型別
10. 函式型別 ( 陳述/表達/可選參數/參數默認/重載/剩餘參數 )

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### 練習：typescript 本週重點觀念習題
**題目一:** (基本型別)
Create a variable called highScore that can be a number OR a boolean

**題目二:** (array 數組型別 & 聯合型別)
create an array called stuff
it can be an array of numbers OR an array of strings
it cannot be an array of numbers and strings (mixed together)

**題目三** ( 函式型別 )
Write a function called greet that accepts a single string OR an array of strings
It should print "Hello, <name>" for that single person OR greet each person in the array with the same format

**題目四** ( interface )
Given this interface:

    interface Cryable {
      cry(): string;
    }

Select the answer below that is a valid implementation of the Cryable interface

   // option A
    const human: Cryable = {
        cry(person:string) {
            return "BOO HOO"
        }
    }

   // option B
    const human: Cryable = {
        cry() {
            console.log("BOO HOO")
        }
    }

   // option C
    const human: Cryable = () => {
        return "BOO HOO"
    }

   // option D
     const human: Cryable = {
        cry() {
           return "BOO HOO"
        }
    }

**題目五** ( interface )
Which of the following Addable interfaces uses INVALID TypeScript syntax:

   // option A
     interface Addable {
        add(x:number, y:number):number;
    }

   // option B
     interface Addable {
        add:(x:number, y:number) => number;
    }

   // option C
     interface Addable {
        add(x:number, y:number) {
            number;
        }
    }

**題目六** ( function )
Given the following function definition:

 function multiply(x,y) {
        return x*y
    }

What are the TypeScript types of the parameters x and y ?
A. number
B. any
C. unkown
D. undefined

**題目七** ( function )
Given the following secondsInDay function:

function secondsInDay() {
  return 24 * 60 * 60;
}

What return type does TypeScript assign to it?
A. Error: missing required return annotation
B. any
C. number
D. undefined

**題目八** ( function )
What return type does TypeScript infer for the following function:

function doNothing() {
  2 + 2;
}

A. number
B. undefined
C. any
D. void

**題目九** ( function )
Write a function called "twoFer" that accepts a person's name
It should return a string in the format "one for <name>, one for me"
If no name is provided, it should default to "you"

twoFer() => "One for you, one for me"
twoFer("Elton") => "One for Elton, one for me"

**題目十** ( function )
Write a isLeapyear() function that accepts a year and returns true/false depending on if the year is a leap year

    isLeapYear(2012) => true
    isLeapYear(2013) => false

To determine whether a year is a leapyear, use this "formula":
A YEAR IS A LEAPYEAR IF
- year is a multiple of 4 AND not a multiple of 100
OR...
- year is a multiple of 400
hint - use modulo

<!-- 答案網址: https://codepen.io/bruno-yu/pen/dyaqNjm?editors=0010 -->
| 名稱 | 回報網址 |
| -------- | :--------: |
| Bruno | [codepen](https://codepen.io/bruno-yu/pen/YzBONxe?editors=0010) |
| 真真 | [codepen](https://codepen.io/JudithCrocodile/pen/qBgLNVd?editors=1010) |
| 家欣 | [codepen](https://codepen.io/scwlvjdw-the-bashful/pen/MWLzPGV?editors=0011) |
| | |
|| |

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